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High doses of Vitamin B6 might help to reduce anxiety, according to the results of a new double-blind placebo-controlled study published in Human Psychopharmacology: Clinical and Experimental. The research provides preliminary evidence that B6 supplementation can produce behavioral outcomes by boosting inhibitory neurotransmitters in the brain.

Vitamin B6 is a water-soluble vitamin that is part of the vitamin B complex. It can be found in a variety of foods, including meat, poultry, fish, beans, nuts, and bananas. Vitamin B6 is important for immune function, red blood cell metabolism, and nervous system development. It also plays an important role in converting the excitatory neurotransmitter glutamate into the inhibitory neurotransmitter gamma-aminobutyric acid (GABA).

The new research was inspired by previous work that suggested B vitamins could enhance the production of GABA.

“Back in 2017 a colleague from the University of York gave a talk at my university that included results of a study in which he had compared the effects of a spoonful of marmite for a month to peanut butter,” said study author David Field, an associate professor at the University of Reading.

“His hypothesis was that the B vitamins and other ingredients in the marmite would cause the brain to make slightly more of the inhibitory neurotransmitter GABA. He tested this by measuring the electrical (EEG) response of the brain to specific types of visual stimuli that are known to engage inhibitory neurons that use in the neurotransmitter GABA in the visual cortex.”

“His results showed that the activity level in the brain was reduced by the marmite, as he’d predicted. I reviewed the resulting paper, and I thought it was plausible that GABA levels had increased, but probably not because of B6 in marmite as the authors claimed – because there is very little B6 in marmite. I thought that an additive or synergistic effect of the different ingredients in marmite was the most likely explanation of the findings.”

“I decided to follow up the York study, and I wanted to know which individual B vitamins might be capable of increasing GABA,” Field explained. “There is a lot of Vitamin B12 in marmite, so I tried that. And although Vitamin B6 is only minimally present in marmite, it is known to be needed for the conversion of glutamate to GABA, so I tried that too – in comparison to placebo.”

“Secondly, I reasoned that if GABA was increased in visual cortex and this subtly influenced visual perception, then elsewhere in the brain this could act to inhibit unwanted thoughts and calm the brain down, so reducing anxiety. For this reason, I also measure the anxiety levels of our rather stressed-out university student participants.”

In the study, 478 participants were randomly assigned to receive either B6, B12, or placebo tablets. The participants were asked to ingest one tablet per day with food for about one month. Prior to supplementation, the participants completed assessments of anxiety and depression. They completed these assessments again after the one-month period, along with tests of visual processing and cognition.

Vitamin B12 had little effect compared to placebo over the trial period, but Vitamin B6 made a statistically reliable difference. The researchers found that B6 supplementation reduced anxiety symptoms and also appeared to influence visual contrast sensitivity, or the ability to see small differences in brightness between an object and its background.

When there’s a strong contrast between an object and its background, our eyes are very good at seeing even small differences in brightness. But when the contrast is weak, it can be hard to see even large differences in brightness. The contrast between an object and its background can also affect something called “surround suppression.” Surround suppression is when our brain ignores information from the part of the field that surrounds an object.

Field and his colleagues found evidence that B6 supplementation increased the ability to detect low contrast visual targets when a suppressive background pattern was present. According to the researchers, “the pattern of results produced by Vitamin B6 supplementation in this visual paradigm is the same as that produced by the GABA agonist alprazolam,” a sedative that is used to treat anxiety and panic disorders.

However, B6 supplementation did not have a statistically significant effect on depression symptoms, binocular rivalry reversal rate, or a tactile test battery.

“Really the best take home message is that a healthy, Mediterranean style, diet is likely to be beneficial for all aspects of health, including mental health and wellbeing,” Field told PsyPost. “But possibly there is an argument for taking vitamin supplements when stressed – the body burns more B vitamins when you are stressed and stores can become depleted – if diet is more western than Mediterranean.”

“Regarding B6 and anxiety, it is early days in this research and B6 should not be seen as a replacement for any other treatments that a doctor has prescribed. Some reasons are that it is likely that some but not all of our participants responded to the intervention, and the effect size has not been evaluated to see if it is clinically relevant.”

The tablets used in the study each contained 100 mg of B6.

“The dose of B6 that we used is recommended as safe for long term use, and can be purchased in shops,” Field said. “However, recent research has shown that a very small minority of people experience side effects at lower doses. These take the form of peripheral neuropathy, which begins with tingling in the extremities. None of our study participants reported this, and it is rare. But if anybody experience that they should stop taking the supplement.”

“I have identified several other vitamins and micronutrients that theoretically should also reduce calm the brain and reduce anxiety, and these act via different metabolic pathways than B6,” the researcher added. “My hope is that the effects of these will be additive with B6, and in combination the effect size will be clinically meaningful. However, I am still in the early stages of this research, and I have not tested the other potential ingredients yet.”

The study, “High‐dose Vitamin B6 supplementation reduces anxiety and strengthens visual surround suppression“, was authored by David T. Field, Rebekah O. Cracknell, Jessica R. Eastwood, Peter Scarfe, Claire M. Williams, Ying Zheng, and Teresa Tavassoli.

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